Making up approximately 1% of live births, congenital heart defects are the most common birth defect. In the severe forms, surgery on the vasculature is the only option for treatment. Often multiple surgeries to replace outgrown vascular conduits are required as the patient matures. The child’s own mesenchymal stem cells (MSCs), which can differentiate into smooth muscle cells, provide the opportunity to produce tissue engineered vascular grafts that grow, repair and remodel, thereby eradicating the need for additional surgeries. We have recently isolated and characterized MSCs derived from tissue normally regarded as waste in congenital heart surgeries, the thymus. We’re now investigating the use of these cells to tissue engineer vascular grafts that can be used in paediatric corrective heart surgery. This study aimed to assess cell growth/viability of cells seeded onto the CorMatrix (naturally occurring scaffold routinely used in cardiac surgery) and to examine at high resolution the structure and topography of tissue-engineered patches. Using live-imaging fluorescence microscopy we showed live cells on the MSCs seeded-CorMatrix. We then inspected the topography of the two sides of the CorMatrix using scanning electron microscopy (SEM). Our data showed that one side seemed to have a smoother surface than the other. However, when seeded with MSCs, both CorMatrix sides showed a similar capacity at homing cells. These seeded MSCs formed a layer with visible cell-cell and cell-matrix connections. Both CorMatrix sides showed the same capacity at homing endothelial cells. Higher seeding density of MSCs on the corMatrix produced a viable cell layer that perfectly covered the CorMatrix surface. In conclusion, we showed that thymus MSCs and endothelial cells are able to grow on CorMatrix for potential use as a graft for surgical repair of congenital heart defects.